Driving a synchronous motor so that it emulates a twin-shaft gas turbine engine

This paper presents a model-based control method for using a vector controlled synchronous motor to emulate the behaviour of a twin-shaft gas turbine engine as it drives an electric generator supplying power to steady-state and dynamic loads. The aim of this approach is to provide an in-door test-bed for the generator itself, in the absence of the engine that will eventually be used as prime mover. The control method is validated on a much-smaller (benchtop-scale) hardware-in- the-loop (HIL) implementation of the engine emulator system. The motor speed controller tracks the output speed of a simulated real-time engine model in order to generate appropriate voltage and frequency demands for the variable speed inverter that drives the motor. The inertia of the synchronous motor is varied by adding inertial loading to its shaft in order to study the effect of emulating a prime mover with a higher inertia than the emulator motor. Experimental results show that the emulator motor is able to track the engine speed with excellent accuracy when its inertia is lower than the engine model. But, when the emulator motor inertia is higher than the engine model the speed tracking performance of the motor presents a dynamic lag and it requires a larger control effort.